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authorMiklos Szeredi <mszeredi@suse.cz>2014-12-13 00:59:49 +0100
committerMiklos Szeredi <mszeredi@suse.cz>2014-12-13 00:59:49 +0100
commitab508822cab4c84f07373cd6ad107a1fd1362831 (patch)
treed612d840a78d2c1f1ead7d0cd699becb68caeb95
parent3b7a9a249a93e68b7bb318de40e64d3b68ba1a6d (diff)
downloadlinux-ab508822cab4c84f07373cd6ad107a1fd1362831.tar.gz
ovl: improve mount helpers
Move common checks into ovl_mount_dir() helper. Create helper for looking up lower directories. Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
-rw-r--r--fs/overlayfs/super.c125
1 files changed, 73 insertions, 52 deletions
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index a177028..592370f 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -669,24 +669,6 @@ static void ovl_unescape(char *s)
}
}
-static int ovl_mount_dir(const char *name, struct path *path)
-{
- int err;
- char *tmp = kstrdup(name, GFP_KERNEL);
-
- if (!tmp)
- return -ENOMEM;
-
- ovl_unescape(tmp);
- err = kern_path(tmp, LOOKUP_FOLLOW, path);
- if (err) {
- pr_err("overlayfs: failed to resolve '%s': %i\n", tmp, err);
- err = -EINVAL;
- }
- kfree(tmp);
- return err;
-}
-
static bool ovl_is_allowed_fs_type(struct dentry *root)
{
const struct dentry_operations *dop = root->d_op;
@@ -706,6 +688,71 @@ static bool ovl_is_allowed_fs_type(struct dentry *root)
return true;
}
+static int ovl_mount_dir_noesc(const char *name, struct path *path)
+{
+ int err;
+
+ err = kern_path(name, LOOKUP_FOLLOW, path);
+ if (err) {
+ pr_err("overlayfs: failed to resolve '%s': %i\n", name, err);
+ goto out;
+ }
+ err = -EINVAL;
+ if (!ovl_is_allowed_fs_type(path->dentry)) {
+ pr_err("overlayfs: filesystem on '%s' not supported\n", name);
+ goto out_put;
+ }
+ if (!S_ISDIR(path->dentry->d_inode->i_mode)) {
+ pr_err("overlayfs: '%s' not a directory\n", name);
+ goto out_put;
+ }
+ return 0;
+
+out_put:
+ path_put(path);
+out:
+ return err;
+}
+
+static int ovl_mount_dir(const char *name, struct path *path)
+{
+ int err = -ENOMEM;
+ char *tmp = kstrdup(name, GFP_KERNEL);
+
+ if (tmp) {
+ ovl_unescape(tmp);
+ err = ovl_mount_dir_noesc(tmp, path);
+ kfree(tmp);
+ }
+ return err;
+}
+
+static int ovl_lower_dir(const char *name, struct path *path, long *namelen,
+ int *stack_depth)
+{
+ int err;
+ struct kstatfs statfs;
+
+ err = ovl_mount_dir(name, path);
+ if (err)
+ goto out;
+
+ err = vfs_statfs(path, &statfs);
+ if (err) {
+ pr_err("overlayfs: statfs failed on '%s'\n", name);
+ goto out_put;
+ }
+ *namelen = max(*namelen, statfs.f_namelen);
+ *stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth);
+
+ return 0;
+
+out_put:
+ path_put(path);
+out:
+ return err;
+}
+
/* Workdir should not be subdir of upperdir and vice versa */
static bool ovl_workdir_ok(struct dentry *workdir, struct dentry *upperdir)
{
@@ -726,7 +773,6 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
struct dentry *root_dentry;
struct ovl_entry *oe;
struct ovl_fs *ufs;
- struct kstatfs statfs;
struct vfsmount *mnt;
unsigned int i;
int err;
@@ -756,48 +802,23 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
if (err)
goto out_put_upperpath;
- err = ovl_mount_dir(ufs->config.lowerdir, &lowerpath);
- if (err)
- goto out_put_workpath;
-
- err = -EINVAL;
- if (!S_ISDIR(upperpath.dentry->d_inode->i_mode) ||
- !S_ISDIR(lowerpath.dentry->d_inode->i_mode) ||
- !S_ISDIR(workpath.dentry->d_inode->i_mode)) {
- pr_err("overlayfs: upperdir or lowerdir or workdir not a directory\n");
- goto out_put_lowerpath;
- }
-
if (upperpath.mnt != workpath.mnt) {
pr_err("overlayfs: workdir and upperdir must reside under the same mount\n");
- goto out_put_lowerpath;
+ goto out_put_workpath;
}
if (!ovl_workdir_ok(workpath.dentry, upperpath.dentry)) {
pr_err("overlayfs: workdir and upperdir must be separate subtrees\n");
- goto out_put_lowerpath;
- }
-
- if (!ovl_is_allowed_fs_type(upperpath.dentry)) {
- pr_err("overlayfs: filesystem of upperdir is not supported\n");
- goto out_put_lowerpath;
- }
-
- if (!ovl_is_allowed_fs_type(lowerpath.dentry)) {
- pr_err("overlayfs: filesystem of lowerdir is not supported\n");
- goto out_put_lowerpath;
- }
-
- err = vfs_statfs(&lowerpath, &statfs);
- if (err) {
- pr_err("overlayfs: statfs failed on lowerpath\n");
- goto out_put_lowerpath;
+ goto out_put_workpath;
}
- ufs->lower_namelen = statfs.f_namelen;
+ sb->s_stack_depth = upperpath.mnt->mnt_sb->s_stack_depth;
- sb->s_stack_depth = max(upperpath.mnt->mnt_sb->s_stack_depth,
- lowerpath.mnt->mnt_sb->s_stack_depth) + 1;
+ err = ovl_lower_dir(ufs->config.lowerdir, &lowerpath,
+ &ufs->lower_namelen, &sb->s_stack_depth);
+ if (err)
+ goto out_put_workpath;
err = -EINVAL;
+ sb->s_stack_depth++;
if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) {
pr_err("overlayfs: maximum fs stacking depth exceeded\n");
goto out_put_lowerpath;